The current proposal is aimed at providing the PI with extensive training in receptor signaling with reference to its clinical implications along with formal courses at the graduate level to enhance his research and laboratory skills. The experienced sponsor and co-sponsor, along with a highly interactive basic-research environment at department of Medicine at the University of Illinois at Chicago, offer a great training opportunity for the PI to achieve his career goals in becoming an independent research investigator in the area of the signaling mechanisms. The proposed studies are aimed at examining the molecular and functional interaction of atrial natriuretic peptide (ANP) and nitric oxide (NO) signaling. Both ANP and NO increase intracellular cyclic GMP (cGMP) levels thus leading to reduction in arterial blood pressure and inhibition of renal tubular sodium transport. Studies in specific Aim 1 will determine the interacting domains of NOGCb1 and GCA utilizing immunoprecipitations and immunofluorescence techniques. We will also identify proteins interacting with GCA and NOGCb1 , possibly novel ones by using novel Tandem Affinity Purification (TAP) method. In specific Aim 2, we will focus on evaluating the functional impact of the association of NOGCb1 with GCA on ANP-mediated stimulation of cGMP, cGMP-dependent protein kinase (cGK), and cGMP phosphodiesterase (PDE) using RNAi technology. In specific Aim 3 we will determine the effect of reducing NOGCb1 on ANP signaling in renal tubular sodium handling by measuring 22Na uptake in renal epithelial cells transfected with RNAi against NOGCb1 and treated with ANP. The functional interaction between ANP and NO signaling may provide new understanding to diseases associated with reduced NO signaling, such as renal glomerular disease, chronic and acute renal failure, and hypertension.